1) Field of the Invention
The present invention relates to a lagging device, especially to a lagging device which can be applied to the surface of a current object.
2) Description of the Prior Art
As the advance of technology, the warn-keeping or lagging of object is performed by electric heater or electric wrap other than by fire. The conventional electric wraps are used to keep user warm at clod weather or condition. However, they are bulky in application. The electric wrap generally comprises of a plug connected to AC power source and coil for generating heat. The user can put the portion with thermal coil to the location required to keep warm. However, the conventional electric wrap has following problems:
1. The heating coil is liable to oxidation and break and hard to repair due to the arrangement thereof being within the wrap. PA1 2. The heating coil is generally controlled by a thermal sensor to keep constant power. However, the thermal sensor in different environment may have different response, even malfunction. PA1 3. The heating coil may generate dangerous spark.